The invention relates to a switch, with manual closing and opening and with thermal release, comprising in a housing an actuating member coupled to a control arm which is movable about a first fixed pivot and the end of which is coupled by a first articulation to a first end of a connecting rod to constitute a knee joint, a second end of the connecting rod being coupled by a second articulation to a loading lever, a first end of which loading lever is abutted against a latch displaced rotatably about a second fixed pivot by the movement of overload bi-metallic strips, a second end of the loading lever co-operating with a transmission lever which is associated with the movable contacts, and pivots about a third pivot. Such known switches can be used both for the closing and for the breaking of monophase circuits and for that of three-phase circuits, in which they must usually carry out the feeding and protection of electric motors.
In this latter case, the presence of three thermal bi-metallic strips makes the apparatus relatively bulky, such that it has been sought to dispose each of these respectively in planes passing through the input and output terminals in order to obtain the minimum width which in practice is imposed by the length of the escape paths between the terminals.
Amongst the measures which can be put to use to obtain a reduced width there can be mentioned those which consist in increasing the height and length of the apparatus, without nevertheless pushing these possibilities too far, because reason of the presence of other apparatus on the control panels.